The present invention relates in general to an automotive heating, ventilation, air conditioning (HVAC) system having an electrically controlled blower motor, and, more specifically, to structures for obtaining even diffusion of air simultaneously with improving cooling of the blower controller.
In a typical automotive HVAC system, a blower delivers fresh or recirculated air to heat exchangers (e.g., an evaporator) which is then distributed to the passenger cabin via ducts. A diffuser couples the air stream from the blower to the evaporator. Due to space requirements, the diffuser turns the air stream for delivery to the evaporator. The blower/diffuser combination produces a high speed, non-uniform flow that tends to produce high flows on the outer periphery of the diffuser due to centrifugal forces.
A uniform velocity distribution at the diffuser outlet and in the evaporator is very desirable to ensure efficient evaporator performance, higher air flow, and reduced noise generation as the air passes through the evaporator core. Various vanes and wall guides have been added to the diffuser to improve the uniformity of the air flow. One example is U.S. patent application publication 2010/0074743A1 of Jairazbhoy et al, entitled “Air Diffuser for a HVAC System,” which is hereby incorporated by reference in its entirety.
The diffuser is normally made as a molded plastic part. It has not been possible to make interior vanes of sufficient height extending from a corresponding wall due to limitations in the molding process and limitations associated with handling of the part after molding (e.g., breakage of the vanes). Therefore, vanes can affect the air flow near to the diffuser walls but are less able to affect air flow at the center of the diffuser. Furthermore, the die draw of the molding process does not allow vanes to extend from walls that are perpendicular to one another (i.e., vanes cannot extend from both the curved outer peripheral wall and either of the transverse (i.e., floor and ceiling) walls in the same molded section).
For similar reasons, wall guides have a greater influence on air flow in the regions of the walls. Known vanes and wall guides may be insufficient to obtain a desired uniformity of a diffused air stream when it becomes necessary to manipulate flow at the core, central portion of the diffuser.
The typical automotive HVAC system allows a user to select a rotating speed of the blower via a switch or dial. A variable blower control (VBC) module is an electronic controller that is mounted to the outside of the diffuser between the blower and the evaporator. Cooling fins penetrate the diffuser wall so that they benefit from the air flow within the diffuser. The VBC module has been conventionally mounted on a relatively flat exterior surface of the diffuser wall.